Foldable display device

ABSTRACT

A foldable display device includes a flexible display module having an electroluminescent unit, a flexible functional module on the flexible display, the flexible functional module having at least one function selected from the group of polarization, a color filtering, color conversion, a touch sensing, and biometric information recognition, and a flexible window module on the flexible functional module. A side surface of the flexible display module, a side surface of the flexible functional module, and a side surface of the flexible window module may be located on a first plane at a first side portion. An inner angle formed by an upper surface of the flexible window module emitting light and the first plane may be an acute angle at the first side portion.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This is a continuation application of U.S. patent application Ser. No.16/216,393 filed Dec. 11, 2018 (now pending), the disclosure of which isincorporated herein by reference in its entirety. U.S. patentapplication Ser. No. 16/216,393 claim priority benefit of Korean PatentApplication No. 10-2018-0055195 filed on May 15, 2018; in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference in its entirety for all purposes.

BACKGROUND 1. Field

Example embodiments relate to a foldable display device.

2. Description of the Related Art

A display device is a device for displaying an image and includes adisplay panel such as an organic light emitting display panel or aliquid crystal display panel.

A mobile terminal includes a display device for providing an image to auser. A foldable display device or a bendable display device having astructure that can be folded and unfolded to provide a larger screenonly at the time of use is desirable.

SUMMARY

Example embodiments are directed to a foldable display device. Thefoldable display device may comprise a flexible display module, aflexible functional module, and a flexible window module. The flexibledisplay module may have an electroluminescent unit. The flexiblefunctional module may be located on the flexible display. The flexiblefunctional module may have at least one function selected from the groupof polarization, color filtering, color conversion, touch sensing, andbiometric information recognition. That is, the flexible functionalmodule may have at least one function of the polarization, the colorfiltering, the color conversion, the touch sensing, and/or the biometricinformation recognition. The flexible window module may be located onthe flexible functional module. At a first side portion, a side surfaceof the flexible display module, a side surface of the flexiblefunctional module, and a side surface of the flexible window module maybe located on a first plane. At the first side portion, an inner angleformed by an upper surface of the flexible window module emitting lightand the first plane may be an acute angle.

The foldable display device may further comprise a cushion module. Thecushion module may be located under the flexible display module. A sidesurface of the cushion module may be located on a second plane locatedinside the first plane at the first side portion.

The first side portion may be located in a foldable region.

At a second side portion substantially different from the first sideportion and located in a non-foldable region, the side surface of theflexible display module may be located on a third plane. At the secondside portion, the side surface of the flexible window module may belocated on a fourth plane located outside the third plane.

The side surface of the flexible functional module may be located on afifth plane located inside the third plane at the second side portion.

The foldable display device may further comprise a cushion module. Thecushion module may be located under the flexible display module. A sidesurface of the cushion module may be located on a sixth plane locatedinside the third plane at the second side portion.

At a third side portion substantially different from the first andsecond side portions and located in the non-foldable region, theflexible display module may include a bent portion.

At the third side portion, an outermost portion of the bent portion maybe aligned to be located just under the side surface of the flexiblewindow module.

The second side portion may be located between the first side portionand the third side portion.

The flexible display module may include a bent portion at a third sideportion substantially different from the first side portion and locatedin a non-foldable region.

At the third side portion, an outermost portion of the bent portion maybe aligned to be located just under the side surface of the flexiblewindow module.

The flexible display module may include a lower inorganic encapsulationstructure and an upper encapsulation structure which may have a lowersurface including only at least one inorganic material. The flexibledisplay module may include an inorganic-inorganic contact closed loop atwhich the lower surface of the upper encapsulation structure may contactthe lower inorganic encapsulation structure. The electroluminescent unitmay be located between the lower inorganic encapsulation structure andthe upper encapsulation structure. The electroluminescent unit may besurrounded by the inorganic-inorganic contact closed loop in a planview. The inorganic-inorganic contact closed loop may be spaced apartfrom the side surface of the flexible display module.

Example embodiments are directed to a foldable display device. Thefoldable display device may comprise a cushion module and an uppermember. The upper module may be located on the cushion module. The uppermember may include at least one selected from the group of a flexibledisplay module, a flexible functional module, and a flexible windowmodule. That is, the upper member may include at least one of a flexibledisplay module, a flexible functional module, and/or a flexible windowmodule. The flexible display module may be substantially surrounded by afirst side portion and a second side portion. The first side portion mayhave a first side surface. The second side portion may have a secondside surface of a substantially different profile from the first sidesurface. The second side portion may have a substantially larger lengththan the first side portion. The flexible display module may have anelectroluminescent unit. The flexible functional module may besubstantially surrounded by a third side portion having a third sidesurface and a fourth side portion having a fourth side surface of asubstantially different profile from the third side surface. The fourthside portion may have a substantially larger length than the third sideportion. The flexible functional module may have at least one functionselected from the group of polarization, color filtering, colorconversion, touch sensing, and biometric information recognition. Thatis, the flexible functional module may have at least one function of thepolarization, the color filtering, the color conversion, the touchsensing, and/or the biometric information recognition. The flexiblewindow module may be substantially surrounded by a fifth side portionhaving a fifth side surface and a sixth side portion having a sixth sidesurface of a substantially different profile from the fifth sidesurface. The sixth side portion may have a substantially larger lengththan the fifth side portion.

The upper member may include the flexible display module, the flexiblefunctional module, and the flexible window module. The flexiblefunctional module may be located on the flexible display module. Theflexible window module may be located on the flexible functional module.The second side surface of the flexible display module, the fourth sidesurface of the flexible functional module, and the sixth side surface ofthe flexible window module may be located on a same etching surface.

The same etching surface may be formed using a laser having a pulsewidth substantially shorter than about 1 nanosecond.

The same etching surface may be formed by the laser. A progressdirection of the laser may be a direction that may be tilted at about0.1 to about 5 degrees toward a side portion of the flexible windowmodule from a center of the flexible window module with respect to anemission direction of light that may be emitted vertically to an uppersurface of the flexible window module.

The flexible display module may include a lower inorganic encapsulationstructure and an upper encapsulation structure having a lower surfaceincluding only at least one inorganic material. The flexible displaymodule may include an inorganic-inorganic contact closed loop at whichthe lower surface of the upper encapsulation structure may contact thelower inorganic encapsulation structure. The electroluminescent unit maybe located between the lower inorganic encapsulation structure and theupper encapsulation structure. The electroluminescent unit may besurrounded by the inorganic-inorganic contact closed loop in a planview. The inorganic-inorganic contact closed loop may be spaced apartfrom the first and second side surfaces of the flexible display module.

Example embodiments are directed to a foldable display device. Thefoldable display device may comprise a first non-foldable region, asecond non-foldable region, a foldable region, and a bent region. Thefirst non-foldable region may have a first outer side extending to havea first length in a first direction and an inner side located to besubstantially opposite to the first outer side and extending in thefirst direction. The second non-foldable region having an outer sideextending to have a second length substantially larger than the firstlength in the first direction and an inner side located to besubstantially opposite to the outer side and extending in the firstdirection. The foldable region may extend in the first direction betweenthe inner side of the first non-foldable region and the inner side ofthe second non-foldable region. The bent region may be connected to theouter side of the second non-foldable region. The bent region may have apad portion. The bent region may extend to have a third lengthsubstantially smaller than the second length in the first direction.

The third length may be about 50% to about 95% of the second length.

The first non-foldable region may further include a second outer sideand a third outer side. The second outer side may be located to besubstantially opposite to the inner side of the first non-foldableregion and may extend in the first direction to have a fourth lengthsubstantially smaller than the second length. The third outer side mayextend in a second direction substantially different from the firstdirection to connect the first outer side and the second outer side.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of skill in the art by describingin detail example embodiments with reference to the attached drawings inwhich:

FIGS. 1 to 10 illustrate diagrams of a foldable display device andstages of a manufacturing method of the foldable display deviceaccording to an example embodiment;

FIG. 11 illustrates a plan view depicting a foldable display deviceaccording to an example embodiment; and

FIG. 12 illustrates a plan view depicting a foldable display deviceaccording to an example embodiment.

DETAILED DESCRIPTION

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to the exampleembodiments set forth herein. Rather, these example embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey exemplary implementations to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. It will also be understood thatwhen a layer or element is referred to as being “on” another layer orsubstrate, it can be directly on the other layer or substrate, orintervening layers may also be present. Further, it will be understoodthat when a layer is referred to as being “under” another layer, it canbe directly under, and one or more intervening layers may also bepresent. In addition, it will also be understood that when a layer isreferred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent. Like reference numerals refer to like elements throughout. Asused herein, the expressions “at least one,” “one or more,” and “and/or”are open-ended expressions that are both conjunctive and disjunctive inoperation. For example, each of the expressions “at least one selectedfrom the group of A, B, and C,” “at least one of A, B, and C,” “at leastone of A, B, or C,” “one or more of A, B, and C,” “one or more of A, B,or C,” and “A, B, and/or C” includes the following meanings: at leastone A alone; at least one B alone; at least C alone; both at least one Aand at least one B together; both at least one A and at least one Ctogether; both at least one B and at least one C together; and all threeof at least one A, at least one B, and at least one C together. Further,these expressions are open-ended, unless expressly designated to thecontrary by their combination with the term “consisting of.” Forexample, the expression “at least one selected from the group of A, B,and C” may also include a fourth member, whereas the expression “atleast one selected from the group consisting of A, B, and C” does not.As used herein, the expression “or” is not an “exclusive or” unless itis used in conjunction with the phrase “either.” For example, theexpression “A, B, or C” includes A alone; B alone; C alone; both A and Btogether; both A and C together; both B and C together; and all three ofA, B and, C together, whereas the expression “either A, B, or C” meansone of A alone, B alone, and C alone, and does not mean any of both Aand B together; both A and C together; both B and C together; and allthree of A, B and C together.

FIGS. 1 to 10 illustrate diagrams of a foldable display device andstages of a manufacturing method of the foldable display deviceaccording to an example embodiment.

FIG. 2 illustrates a cross-sectional view taken along line I-I′ of FIG.1 .

Referring to FIGS. 1 and 2 , a preliminary flexible display module 110may be prepared. The preliminary flexible display module 110 may becomea flexible display module 510 by a subsequent laser cutting process.

The preliminary flexible display module 110 may have a substantiallyrectangular shape in a plan view. For example, the preliminary flexibledisplay module 110 may have a substantially rectangular shape withrounded corners in a plan view. In some example embodiments, thepreliminary flexible display module 110 may have a substantiallyrectangular shape with vertical corners.

Unless otherwise defined, the terms “upper portion” and “upper surface”in a thickness direction in the present specification refer to a displaysurface side that emits light based on the preliminary flexible displaymodule 110 or the flexible display module 510 in the unfolded state andthe terms “lower portion” and “lower surface” refer to an opposite sideof the display surface based on the preliminary flexible display module110 or the flexible display module 510 in the unfolded state. Further,“upper”, “lower”, “left”, and “right” in a plane direction indicate adirection when the display surface is placed at a regular location andviewed from the top. In addition, “outside” indicates a direction towardthe outside of the center of gravity of the foldable display device 100and “inside” indicates a direction toward the center of gravity of thefoldable display device 100. Herein, the term “display device” is adisplay part in an information device such as a television, a mobileterminal for a final human consumer, or in an optical device such as anillumination device.

The preliminary flexible display module 110 may comprise a flexiblesubstrate including a flexible polymeric material such as polyimide orthe like. As a result, the preliminary flexible display module 110 maybe warpable, bendable, foldable, or rollable. Accordingly, the flexibledisplay module 510 obtained by performing the laser cutting process onthe preliminary flexible display module 110 may also be warpable,bendable, foldable, or rollable.

The preliminary flexible display module 110 may include a main regionMR, a bendable region BR, and a sub region SR.

The main region MR may be a substantially flat region located on oneplane. In some example embodiments, at least one edge of the main regionMR other than an edge of the main region MR, which is connected to thebendable region BR, may be warped to form a curved surface or may bevertically bent.

The main region MR may be a display area DA including a plurality ofelectroluminescent units and a non-display area NDA surrounding thedisplay area DA. The non-display area NDA may include aninorganic-inorganic contact closed loop LOOP_C, which surrounds thedisplay area DA in a plan view. The display area DA may be locatedinside the inorganic-inorganic contact closed loop LOOP_C in a planview.

The display area DA may have the substantially rectangular shape or thesubstantially rectangular shape with the rounded corners. In someexample embodiments, the display area DA may have various shapesincluding a substantially square shape or other substantially polygonalshape, a substantially circular shape, a substantially elliptical shape,or the like.

The display area DA may be located at the at least one edge of the mainregion, which is warped to form the curved surface or which isvertically bent. Alternatively, the display area DA may not be locatedat the at least one edge of the main region, which is warped to form thecurved surface or which is vertically bent.

As illustrated in FIG. 1 , the bendable region BR may be connected toone side of the main region MR. For example, a left side of the bendableregion BR may be connected to a right side of the main region MR.

The bendable region BR of the preliminary flexible display module 110may be bent with a curvature such that the sub region SR may face alower surface of the display area DA substantially opposite to an uppersurface of the display area DA. A light is emitted from the uppersurface of the display area DA. The bent bendable region BR will bedescribed below with reference to FIG. 8 .

The sub region SR may extend from the bendable region BR. The sub regionSR may be in substantially parallel with the main region after bendingthe bendable region BR is completed. As described below, the sub regionSR may overlap the main region MR in the thickness direction of thepreliminary flexible display module 110 by bending the bendable regionBR.

Wires may be located in the bendable region BR and the sub region SR.The wires in the bendable region BR may be connected to a circuit layerin the main region MR and may extend to the sub region SR. The subregion SR may include a pad PAD located in a pad portion P_PAD. Thewires extending in the sub region SR may be connected to a circuit board1060 described below via the pad PAD.

As illustrated in FIG. 2 , the preliminary flexible display module 110may include a plurality of organic films 311 to 313 and 332, inorganicfilms 321 to 325, 331, and 333, a transistor TR, and an organicelectroluminescent unit EL.

A first organic flexible film 311 may be an insulating substrate. Thefirst organic flexible film 311 may include a material such as a polymermaterial or the like. Examples of the polymeric material may includepolyethersulfone (PES), polyacrylate (PA), polyarylate (PAR),polyetherimide (PEI), polyethylene naphthalate (PEN), polyethyleneterephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI),polycarbonate (PC), cellulose triacetate (CTA), cellulose acetatepropionate (CAP), or a combination thereof.

A second organic flexible film 312 may be located under the firstorganic flexible film 311. The second organic flexible film 312 maysupport the first organic flexible film 311 and may includesubstantially the same material as the first organic flexible film 311.A double-sided adhesive film 313 may be interposed between the firstorganic flexible film 311 and the second organic flexible film 312. Thesecond organic flexible film 312 may be attached to the first organicflexible film 311 by the double-sided adhesive film 313. Thedouble-sided adhesive film 313 may be a film including an organicmaterial. Examples of the film including the organic material mayinclude an optically clear adhesive (OCA), a pressure sensitive adhesive(PSA) or the like. The first organic flexible film 311, the double-sidedadhesive film 313, and the second organic flexible film 312 mayconstitute a flexible substrate of the preliminary flexible displaymodule 110.

The entirety of the preliminary flexible display module 110 illustratedin FIG. 2 may be formed by integration processes in at least one chamberexcept for a lamination process for attaching the second organicflexible film 312 by using the double-sided adhesive film 313.

A fifth inorganic film 325 may be located on the first organic flexiblefilm 311. Examples of the fifth inorganic film 325 may include a siliconoxide film, a silicon nitride film, a silicon oxynitride film, or acomposite film thereof.

A semiconductor pattern having a source region S, a drain region D, anda channel region C located between the source region S and the drainregion D may be located on the fifth inorganic film 325. The fifthinorganic film 325 may be located between the semiconductor pattern andthe first organic flexible film 311 to increase adhesive force and toblock moisture and oxygen that may be transferred from the first organicflexible film 311 to the semiconductor pattern. However, the fifthinorganic film 325 may be omitted depending on a type of first organicflexible film 311, process conditions, or the like. The source region Sand the drain region D of the semiconductor pattern may be electricallyconnected to a source electrode SE and a drain electrode DE,respectively. The source electrode SE and the drain electrode DE will bedescribed below.

A fourth inorganic film 324 may be located on the fifth inorganic film325 to cover the semiconductor pattern. The fourth inorganic film 324may function as a gate insulating layer. Examples of the fourthinorganic film 324 may include a silicon oxide film, a silicon nitridefilm, a silicon oxynitride film, or a composite film thereof.

A gate conductor including a gate electrode GE may be located on thefourth inorganic film 324. The gate electrode GE may overlap thesemiconductor pattern. Examples of a conductive material included in thegate conductor may include aluminum (Al), silver (Ag), copper (Cu),molybdenum (Mo), chromium (Cr), titanium (Ti), tantalum (Ta), and alloysthereof.

A third inorganic film 323 may be located on the gate conductorincluding the gate electrode GE. Examples of the third inorganic film323 may include a silicon oxide film, a silicon nitride film, a siliconoxynitride film, or a composite film thereof.

The second inorganic film 322 may be located on the third inorganic film323. Examples of the second inorganic film 322 may include a siliconoxide film, a silicon nitride film, a silicon oxynitride film, or acomposite film thereof.

A data conductor including the source electrode SE and the drainelectrode DE may be located on the second inorganic film 322. The sourceelectrode SE and the drain electrode DE may be located on the secondinorganic film 322 to be spaced apart from each other. The dataconductor may include at least one selected from the group of a metal, ametal alloy, a metal nitride, a conductive metal oxide, a transparentconductive material, and a combination thereof. The data conductor maybe a single film or a multilayer film. The single film or the multilayerfilm may include nickel (Ni), cobalt (Co), titanium (Ti), silver (Ag),copper (Cu), molybdenum (Mo), aluminum (Al), beryllium (Be), niobium(Nb), gold (Au), iron (Fe), selenium (Se), tantalum (Ta), and acombination thereof. An alloy formed by adding at least element selectedfrom the group of zirconium (Zr), tungsten (W), niobium (Nb), platinum(Pt), hafnium (Hf), oxygen (O), and nitrogen (N) into a metal of atleast one selected from the group of nickel (Ni), cobalt (Co), titanium(Ti), silver (Ag), copper (Cu), molybdenum (Mo), aluminum (Al),beryllium (Be), niobium (Nb), gold (Au), iron (Fe), selenium (Se),tantalum (Ta), and a combination thereof may be used to form the sourceelectrode SE and the drain electrode DE.

The semiconductor pattern, the gate electrode GE, the source electrodeSE, and the drain electrode DE may constitute a switching element. Asillustrated In FIG. 2 , the switching element may be a top gate typedtransistor. Alternatively, the switching element may be a bottom gatetyped transistor.

The first inorganic film may be located on the second inorganic film 322to cover the data conductor. Examples of the first inorganic film 321may include a silicon oxide film, a silicon nitride film, a siliconoxynitride film, or a composite film thereof. A first contact hole CNT1through which at least a portion of the drain electrode DE is exposedmay be formed through the second inorganic film 322, the third inorganicfilm 323, and the fourth inorganic film 324.

The first to fifth inorganic films 321 to 325 may constitute a lowerencapsulation structure 320.

A lower electrode LE which is an individual electrode may be located onthe first inorganic film 321. The lower electrode LE may be electricallyconnected to the drain electrode DE exposed through the first contacthole CNT1. The lower electrode LE may be an anode which is a holeinjection electrode. The lower electrode LE may be a reflectiveelectrode, a transflective electrode, or a transparent electrode. Thelower electrode LE may include a reflective material.

The lower electrode LE may be a single film. Alternatively, the lowerelectrode LE may be a multilayer film in which two or more materials arestacked.

When the lower electrode LE is the multilayer film, the lower electrodeLE may include a reflective conductive film and a transparent ortranslucent conductive film located on the reflective conductive film.Alternatively, the lower electrode LE may include a reflectiveconductive film and a transparent or translucent conductive film locatedunder the reflective conductive film.

The transparent or translucent conductive film may include at least oneselected from the group of indium tin oxide (ITO), indium zinc oxide(IZO), zinc oxide (ZnO), indium oxide (In2O3), indium gallium oxide(IGO), and a combination thereof.

A pixel defining layer PDL may be located on the lower electrode LE. Thepixel defining layer PDL may include an opening through which at least aportion of the lower electrode LE is exposed. The pixel defining layerPDL may include an organic material or an inorganic material. The pixeldefining layer PDL may include a material such as a photoresist, apolyimide resin, an acrylic resin, a silicon compound, a polyacrylicresin, or the like.

An intermediate layer IL may be located on the lower electrode LE andthe pixel defining layer PDL. The intermediate layer IL may be locatedon at least a region exposed through the opening of the pixel defininglayer PDL in the lower electrode LE. The intermediate layer IL may coverat least a portion of a side wall of the pixel defining layer PDL.

The intermediate layer IL may emit one color selected from the group ofa red color, a blue color, and a green color. Alternatively, theintermediate layer IL may emit a white color or may emit one colorselected from the group of cyan, magenta, and yellow. The intermediatelayer IL may emit one color of red, blue, and green in one exampleembodiment. When the intermediate layer IL emits the white light, theintermediate layer IL may include an emitting material capable ofemitting the white light. Alternatively, when the intermediate layer ILemits the white light, a red light emitting layer, a green lightemitting layer, and a blue light emitting layer may be stacked in thethickness direction to form the intermediate layer IL.

An upper electrode UE may be located on the intermediate layer IL andthe pixel defining layer PDL. The upper electrode UE may be a commonelectrode continuously formed on the intermediate layer IL and the pixeldefining layer PDL. The upper electrode UE may be a cathode electrode.The upper electrode UE may be the transparent or translucent electrode.

The lower electrode LE, the intermediate layer IL, and the upperelectrode UE may constitute an organic electroluminescent unit EL. Theorganic electroluminescent unit EL may further include a hole injectionlayer HIL, a hole transport layer HTL, an electron transport layer ETL,and an electron injection layer EIL.

An upper encapsulation multilayer film 330 may be located on the upperelectrode UE. The upper encapsulation multilayer film 330 may preventmoisture and air that may be introduced from the outside from permeatinginto the organic electroluminescent unit EL. The upper encapsulationmultilayer film 330 may include a sixth inorganic film 331, an organicfilm 332 and a seventh inorganic film 333.

The sixth inorganic film 331 may be located on the upper electrode UE.The sixth inorganic film 331 may include at least one selected from thegroup of silicon oxide (SiOx), silicon nitride (SiNx), and siliconoxynitride (SiONx).

The organic film 332 may be located on the sixth inorganic film 331. Theorganic film 332 may include one selected from the group of epoxy,acrylate, and urethane acrylate. The organic film 332 may flatten a stepthat may be formed by the pixel defining layer PDL.

The seventh inorganic film 333 may be located on the organic film 332.The seventh inorganic film 333 may include at least one selected fromthe group of silicon oxide (SiOx), silicon nitride (SiNx), and siliconoxynitride (SiONx).

In FIG. 2 , the sixth inorganic film 331 and the seventh inorganic film333 may each be a single layer. Alternatively, at least one selectedfrom the group of the sixth inorganic film 331 and the seventh inorganicfilm 333 may be a multilayer film.

An inorganic-inorganic contact closed loop LOOP_C may be defined on anupper surface of the first inorganic film 321. As illustrated in FIG. 1, the inorganic-inorganic contact closed loop LOOP_C may be a closedloop extending along an outline of the preliminary flexible displaymodule 110 in a plan view. The inorganic-inorganic contact closed loopLOOP_C may be a region in which an inorganic upper surface PLANE1 of thelower encapsulation structure 320 and an inorganic lower surface PLANE2of the upper encapsulation multilayer film 330 directly contact eachother. Penetration of oxygen or moisture between the first inorganicfilm 321 of the lower encapsulation structure 320 and the sixthinorganic film 331 of the upper encapsulation multilayer film 330 may beefficiently prevented by the inorganic-inorganic contact closed loopLOOP_C.

Referring back to FIG. 1 , the preliminary flexible display module 110may be obtained by laser cutting a base flexible display module (notillustrated) along a first path PATH1. The first path PATH1 may be aclosed loop in a plan view. The first path PATH1 may extend outside thebendable region BR and the sub region SR in the vicinity of a first sideE1 of the preliminary flexible display module 110. The first path PATH1may be spaced apart from the inorganic-inorganic contact closed loopLOOP_C in the vicinity of a second side E2, a third side E3, and afourth side E4. The inorganic-inorganic contact closed loop LOOP_C maybe located inside a boundary defined by the first path PATH1 such thatthe first path PATH1 may not meet or contact the inorganic-inorganiccontact closed loop LOOP_C.

A laser light used for the laser cutting may be irradiated in a firstdirection DL1 and/or a second direction DL2 among the first directionDL1, the second direction DL2, and a third direction DL3 illustrated inFIG. 2 toward the lower surface of the preliminary flexible displaymodule 110.

As illustrated in FIG. 2 , the first direction DL1 may form a specificangle θ toward the outside of the preliminary flexible display module110 with respect to a light emission direction ED from the preliminaryflexible display module 110. The specific angle θ may be in a range offrom about 0.1 to about 5 degrees, in a range of from about 0.3 to about3 degrees, or in a range of from about 0.5 to about 2 degrees.

The second direction DL2 may be in substantially parallel with the lightemission direction ED from the preliminary flexible display module 110.

The third direction DL3 may form a specific angle θ toward the inside ofthe preliminary flexible display module 110 with respect to the lightemission direction ED from the preliminary flexible display module 110.

If laser light directed toward the third direction DL3 were to beirradiated onto the lower surface of the preliminary flexible displaymodule 110, the laser light might be reflected by the lower electrode LEor the upper electrode UE in a third reflection direction DRL3 and mightenter the display area DA of the preliminary flexible display module 110by repeated reflections. The organic material contained in theintermediate layer IL may be vulnerable to laser light. Accordingly, ifreflected laser light were to be incident on the display area DA,serious damage to the display area DA of the preliminary flexibledisplay module 110 could occur.

When the laser light directed in the first direction DL1 is irradiatedonto the lower surface of the preliminary flexible display module 110,it might be possible that the laser light may be reflected in the firstreflection direction DRL1 by a material having a reflectioncharacteristic, such as the lower electrode LE or the upper electrode UEincluded in the preliminary flexible display module 110. However, unlikelaser light reflected in a third reflection direction DRL3, laser lightreflected in the first reflection direction DRL1 may be guided to theoutside of the preliminary flexible display module 110. As a result,damage to the display area DA of the preliminary flexible display module110 may be prevented or reduced.

When laser light directed toward the second direction DL2 is irradiatedonto the lower surface of the preliminary flexible display module 110, aportion of the laser light may be reflected in a second reflectiondirection DRL2 by the lower electrode LE or the like. As a result,damage to the display area DA of the preliminary flexible display module110 may be prevented or reduced.

Therefore, using laser light that may reduce a damage possibility of thedisplay area DA by advancing in the first direction DL1 and/or the laserlight that may reduce the damage possibility of the display area DA byadvancing in the second direction DL2 may be advantageous compared withusing laser light that may damage the display area DA by advancing inthe third direction DL3. Furthermore, it is advantageous to use laserlight that advances in the first direction DL1 because, in the secondreflection direction DRL2, reflected laser light may enter a laserapparatus to damage a lens included in the laser apparatus.

Laser light advancing in the first direction DL1 and/or laser lightadvancing in the second direction DL2 may be used during laser cuttingof the preliminary flexible display module 110. As a result, a laseretching surface of a side portion of the preliminary flexible displaymodule 110 may have a reverse tilted structure.

The reverse tilted structure may be formed not only in the case of usinglaser light advancing in the first direction DL1 but also in the case ofusing laser light advancing in the second direction DL2. The reason isthat in the case of using the laser light advancing in the seconddirection DL2, a portion of the preliminary flexible display module 110relatively close to the laser apparatus receives a relatively greateramount of energy than a portion of the preliminary flexible displaymodule 110 that is substantially farther from the laser apparatus.

When laser light directed in the first direction DL1 is used for lasercutting, the side surface of the preliminary flexible display module 110may have an inner angle of about 3 to about 5 degrees with respect tothe light emission direction ED. In example embodiments, when laserlight directed in the second direction DL2 is used for laser cutting,the side surface of the preliminary flexible display module 110 may havean inner angle of about 1 to about 3 degrees with respect to the lightemission direction ED.

As described with reference to FIGS. 1 and 2 , the preliminary flexibledisplay module 110 may be used for manufacturing the foldable displaydevice 100. The preliminary flexible display module 110 may be obtainedby cutting the base flexible display module (not illustrated) along thefirst path PATH1 by using the laser light irradiated in the firstdirection DL1 and/or in the second direction DL2. The damage to thedisplay area DA of the preliminary flexible display module 110 duringlaser cutting may be prevented. Further, the first path PATH1 may besubstantially larger than the inorganic-inorganic contact closed loopLOOP_C and may not contact the inorganic-inorganic contact closed loopLOOP_C. In this regard, if the first path PATH1 were to contact theinorganic-inorganic contact closed loop LOOP_C, the inorganic-inorganiccontact closed loop LOOP_C could be damaged by the laser light, and as aresult, moisture or oxygen could easily penetrate through theinorganic-inorganic contact closed loop LOOP_C.

Referring to FIG. 3 , a preliminary flexible functional module 120 maybe located on the preliminary flexible display module 110. Thepreliminary flexible functional module 120 may be located to overlap thepreliminary flexible display module 110.

A second upper double-sided adhesive film NAD2 illustrated in FIG. 7 maybe interposed between the preliminary flexible functional module 120 andthe preliminary flexible display module 110. The second upperdouble-sided adhesive film NAD2 may be a film having adhesive propertieson both the upper and lower surfaces. For example, the second upperdouble-sided adhesive film NAD2 may be an optically clear adhesive (OCA)or a press sensitive adhesive (PSA). The preliminary flexible functionalmodule 120 may be attached to the preliminary flexible display module110 by the second upper double-sided adhesive film NAD2.

The preliminary flexible functional module 120 may include at least onefunctional layer. The functional layer may be a layer that performs atouch sensing function, a color filtering function, a color conversionfunction, polarization, a biometric information recognition function, orthe like. An example of the biometric information recognition functionmay include a fingerprint recognition function. The functional layer maybe a sheet layer, a film layer, a thin-film layer, a coating layer, apanel, a plate, or the like. The functional layer may be constituted bya single layer. In example embodiments, a functional layer may include aplurality of laminated thin films or coating layers. For example, thefunctional layer may be a touch sensing panel, a color filter, anoptical film, a fingerprint sensing panel, or the like.

The preliminary flexible functional module 120 may include an opticalfilm such as a micro-lens or a prism film. However, if desired, theoptical film may be omitted.

Similar to the main region MR of the preliminary flexible display module110, the preliminary flexible functional module 120 may have asubstantially rectangular shape in a plan view or a substantiallyrectangular shape with rounded corners. The preliminary flexiblefunctional module 120 may have an area that is substantially larger thanan area of the preliminary flexible display module 110.

A first side F1 of the preliminary flexible functional module 120 may belocated inside the first side E1 of the preliminary flexible displaymodule 110 in a plan view. For example, the first side F1 of thepreliminary flexible functional module 120 may be located substantiallycloser toward the center of the area of preliminary flexible displaymodule 110 than the first side E1 of the preliminary flexible displaymodule 110 in a plan view. In a first area A1, a portion of the mainregion MR of the preliminary flexible display module 110 may be exposedby the preliminary flexible functional module 120.

A second side F2, a third side F3, and a fourth side F4 of thepreliminary flexible functional module 120 may be located outside thesecond side E2, the third side E3, and the fourth side E4 of thepreliminary flexible display module 110, respectively. For example, thepreliminary flexible functional module 120 may cover the preliminaryflexible display module 110 in upper, left, and lower directions.

The preliminary flexible functional module 120 may overlap theinorganic-inorganic contact closed loop LOOP_C of the preliminaryflexible display module 110. For example, the preliminary flexiblefunctional module 120 may completely cover the inorganic-inorganiccontact closed loop LOOP_C of the preliminary flexible display module110.

In FIG. 3 , the first side F1 of the preliminary flexible functionalmodule 120 may be located inside the first side E1 of the preliminaryflexible display module 110 in a plan view. Alternatively, the firstside F1 of the preliminary flexible functional module 120 may be locatedoutside the first side E1 of the preliminary flexible display module 110such that the preliminary flexible functional module 120 may completelycover the main region MR of the preliminary flexible display module 110.

Referring to FIG. 4 , a preliminary flexible window module 130 may belocated on the preliminary flexible functional module 120. Accordingly,a preliminary upper structure 10 a including the preliminary flexibledisplay module 110, the preliminary flexible functional module 120, andthe preliminary flexible window module 130 may be formed. Thepreliminary flexible window module 130 may be located to overlap thepreliminary flexible functional module 120 and the preliminary flexibledisplay module 110.

A first upper double-sided adhesive film NAD1 illustrated in FIG. 7 maybe interposed between the preliminary flexible window module 130 and thepreliminary flexible functional module 120. The first upper double-sidedadhesive film NAD1 may be a film having the adhesive properties on boththe upper and lower surfaces similarly to the second upper double-sidedadhesive film NAD2. The preliminary flexible window module 130 may beattached to the preliminary flexible functional module 120 by the firstupper double-sided adhesive film NAD1.

The preliminary flexible window module 130 may cover the main region MRto protect the main region MR. The preliminary flexible window module130 may include the transparent material. The preliminary flexiblewindow module 130 may include plastic. In this case, the preliminaryflexible window module may have a flexible property.

Examples of the plastic included in the preliminary flexible windowmodule 130 may include polyimide, polyacrylate, polymethylmethacrylate(PMMA), polycarbonate (PC), polyethylenenaphthalate (PEN),polyvinylidene chloride, polyvinylidene difluoride (PVDF), polystyrene,ethylene vinylalcohol copolymer, polyethersulfone (PES), polyetherimide(PEI), polyphenylene sulfide (PPS), triacetyl cellulose (TAC), celluloseacetate propionate (CAP), or the like. The preliminary flexible windowmodule 130 may include one or more of the plastic materials listedabove.

Similar to the main region MR of the preliminary flexible display module110, the preliminary flexible window module 130 may have a substantiallyrectangular shape in a plan view or a substantially rectangular shapewith the rounded corners. The preliminary flexible window module 130 mayhave an area that is substantially larger than the area of thepreliminary flexible functional module 120.

A first side G1, a second side G2, a third side G3, and a fourth side G4of the preliminary flexible window module 130 may be located outside thefirst side F1, the second side F2, the third side F3, and the fourthside F4 of the preliminary flexible functional module 120, respectively.The preliminary flexible window module 130 may completely cover thepreliminary flexible functional module 120.

The first side G1 of the preliminary flexible window module 130 mayoverlap the bendable region BR of the preliminary flexible displaymodule 110 in a plan view. For example, the first side G1 of thepreliminary flexible window module 130 may coincide with a bending linethat horizontally bisects the bendable region BR of the preliminaryflexible display module 110 in a plan view. The first side G1 of thepreliminary flexible window module 130 may pass through the center ofthe bendable region BR of the preliminary flexible display module 110such that the preliminary flexible window module 130 may coverapproximately a half of the bendable region BR of the preliminaryflexible display module 110.

Referring to FIG. 5 , an upper structure 10 b including the flexibledisplay module 510, a flexible functional module 520, and a flexiblewindow module 530 may be formed by laser cutting the preliminary upperstructure 10 a including the preliminary flexible display module 110,the preliminary flexible functional module 120, and the preliminaryflexible window module 130 along the second path PATH2. In the lasercutting, a laser process condition may be adjusted such that theirradiation direction may be in the first direction DL1 and/or thesecond direction DL2 described with reference to FIG. 2 . A laser type,energy, an irradiation angle, and the like may be changed in the processof adjusting the laser process condition.

As illustrated in FIG. 7 , the preliminary flexible display module 110,the preliminary flexible functional module 120, and the preliminaryflexible window module 130 may become the flexible display module 510,the flexible functional module 520, and the flexible window module 530,respectively, by the laser cutting along the second path PATH2.

The flexible display module 510, the flexible functional module 520, andthe flexible window module 530 may be substantially the same as thepreliminary flexible display module 110, the preliminary flexiblefunctional module 120, and the preliminary flexible window module 130,respectively, except for their shapes. Accordingly, a redundantdescription will not be repeated.

A portion of the non-display area NDA included in the main region MR ofthe preliminary flexible display module 110 may be removed by the lasercutting along the second path PATH2. Accordingly, the non-display areaNDA may become a reduced non-display area RNDA. Signal wires or drivingcircuits for applying a signal to the display area DA may be located inthe reduced non-display area RNDA. In addition, an outermost blackmatrix may be located in the reduced non-display area RNDA.

In example embodiments, an extension length L1 of the bendable region BRmay be substantially less than a length L2 of one side of the mainregion MR adjacent to the bendable region BR.

Although the flexible display module 510 has been described to includean organic electroluminescent unit, any suitable type of light emittingunit may be applied as long as an image may be displayed by an inputdata signal. For example, the flexible display module 510 may be aliquid crystal flexible display module, a plasma flexible displaymodule, an electrophoretic flexible display module, an electro-wettableflexible display module, a quantum dot light emitting flexible displaymodule, a micro light emitting diode (Micro LED), or the like.

The second path PATH2 may be an opened loop in a plan view. For example,a start point SP and an end point EP of the second path PATH2 may notcoincide with each other. As illustrated in FIG. 5 , the start point SPof the second path PATH2 may be located in the vicinity of a cornerwhere the first side H1 and the second side H2 of the upper structure 10b meet. The end point EP of the second path PATH2 may be located at acorner where the first side H1 and the fourth side H4 of the upperstructure 10 b meet.

The second path PATH2 may be spaced apart from the inorganic-inorganiccontact closed loop LOOP_C by a predetermined interval. For example, theinorganic-inorganic contact closed loop LOOP_C may be located inside thesecond path PATH2. The second path PATH2 may not meet or may not contactthe inorganic-inorganic contact closed loop LOOP_C. If the second pathPATH2 were to contact the inorganic-inorganic contact closed loopLOOP_C, the inorganic-inorganic contact closed loop LOOP_C could bedamaged during laser cutting, and moisture or oxygen could penetratethrough the inorganic-inorganic contact closed loop LOOP_C.

An irradiation angle of laser light irradiated along the second pathPATH2 for cutting the preliminary upper structure 10 a may besubstantially different from the irradiation angle of laser lightirradiated along the first path PATH1 for cutting of the base flexibledisplay module. For example, the laser light irradiated in the seconddirection DL2 may be used during laser cutting of the base flexibledisplay module and the laser light irradiated in the first direction DL1may be used during laser cutting of the preliminary upper structure 10a.

In this case, a first side J1 of the flexible display module 510 mayhave a side surface having an inclination angle corresponding to thesecond direction DL2. A second side J2, a third side J3, and a fourthside J4 of the flexible display module 510 may have side surfaces havingan inclination angle corresponding to the first direction DL1. Forexample, the inclination angle of the laser etching surface on the firstside J1 of the flexible display module 510 and the inclination angle ofthe laser etching surface at the second side J2, the third side J3, andthe fourth side J4 may be substantially different from each other.

The second path PATH2 may be opened to the first side H1 of the upperstructure 10 b. Accordingly, the laser etching surface may be formedonly on the second to fourth sides H2, H3, and H4 of the upper structure10 b.

According to an example embodiment, laser light irradiated to the baseflexible display module along the first path PATH1 of FIG. 1 may be afirst pulse width laser light having a first pulse duration. The laserlight irradiated to the preliminary upper structure 10 a along thesecond path PATH2 of FIG. 5 may be a second pulse width laser lighthaving a second pulse duration substantially shorter than the firstpulse duration. A thickness of the preliminary upper structure 10 a issubstantially larger than the thickness of the base flexible displaymodule. Accordingly, when the pulse width of laser light irradiated tothe preliminary upper structure 10 a is relatively long, undesiredresults may occur. Examples of the undesired results may include thermaldamages to the preliminary upper structure 10 a, molten materialsgenerated on the periphery of a cut surface, and contaminants such ascarbonized foreign matters generated from the preliminary upperstructure 10 a. Thus, to reduce the undesired results, it is desiredthat the second pulse duration is substantially shorter than the firstpulse duration. As an example, when the first pulse width laser is ananosecond pulse laser, the second pulse width laser light may be laserlight having a pulse duration substantially smaller than about 1nanosecond, such as a picosecond pulse laser or a femtosecond pulselaser. As another example, when the first pulse width laser is thepicosecond pulse laser, the second pulse width laser light may befemtosecond pulse laser light.

According to an example embodiment, both the laser light irradiated tothe base flexible display module along the first path PATH1 of FIG. 1and the laser light irradiated to the preliminary upper structure 10 aalong the second path PATH2 of FIG. 5 may be nanosecond pulse laserlight. In this case, it may be desirable to discharge contaminants suchas carbonized foreign matters that may be generated in a large amount atthe time of irradiating the laser light to the preliminary upperstructure 10 a, which is relatively thick, to the outside using anejector provided in a chamber.

According to an example embodiment, both the laser light irradiated tothe base flexible display module along the first path PATH1 of FIG. 1and the laser light irradiated to the preliminary upper structure 10 aalong the second path PATH2 of FIG. 5 may be picosecond pulse laserlight. In this case, the amount of the contaminants such as thecarbonized foreign matters that may be generated at the time ofirradiating the laser to the preliminary upper structure 10 a, which isrelatively thick, may be reduced as compared with the amount in the caseof using nanosecond pulse laser light.

According to an example embodiment, both the laser light irradiated tothe base flexible display module along the first path PATH1 of FIG. 1and the laser light irradiated to the preliminary upper structure 10 aalong the second path PATH2 of FIG. 5 may be femtosecond pulse laserlight. In this case, the amount of the contaminants such as thecarbonized foreign matters that may be generated at the time ofirradiating the laser to the preliminary upper structure 10 a, which isrelatively thick, may be reduced as compared with the amount in the caseof using nanosecond pulse laser light.

FIG. 7 illustrates a cross-sectional view taken along line I-I of FIG. 6. FIG. 8 illustrates a cross-sectional view taken along line II-II ofFIG. 6 . FIG. 9 illustrates a cross-sectional view taken along lineIII-III′ of FIG. 6 . FIG. 10 illustrates a cross-sectional view takenalong line IV-IV′ of FIG. 6 .

Referring to FIGS. 6 to 10 , a lower flexible module 540 and a rigidfilm 550 may be attached to a lower portion of the upper structure 10 b.Subsequently, the sub region SR may be attached to the lower portion ofthe rigid film 550 by bending the bendable region BR at the lowerportion of the rigid film 550 to complete the foldable display device100.

As illustrated in FIG. 6 , the foldable display device 100 may include afoldable region FR. The foldable region FR will be described belowtogether with the rigid film 550.

The foldable display device 100 may be bent based on a folding axisAXIS_F. Here, the folding axis AXIS_F may cross a second side K2 and afourth side K4 of the foldable display device 100 not adjacent to thebendable region BR of the flexible display module 510. The foldabledisplay device 100 may be capable of being switched between a foldedstate and an unfolded state based on the folding axis AXIS_F.

Herein, the term “foldable” should be construed as including all ofpartial folding, full folding, rollable, in-folding, out-folding, andflexibility. The foldable region FR will be described below withreference to FIG. 8 after describing the lower flexible module 540 andthe rigid film 550.

The lower flexible module 540 may overlap the flexible display module510 in the thickness direction. For example, the lower flexible module540 may be located under the flexible display module 510.

The lower flexible module 540 may include at least one functional layer.The functional layer may be a layer performing a heat dissipationfunction, an electromagnetic wave shielding function, a groundingfunction, a buffering function, a strength enhancement function, asupport function, a bonding function, a pressure sensing function, adigitizing function, or the like. The functional layer may be a supportsubstrate, a heat dissipation layer, an electromagnetic wave shieldinglayer, an impact absorbing layer, a bonding layer, a pressure sensor, adigitizer, or the like. When the lower flexible module 540 includes theimpact absorbing layer, the lower flexible module 540 may be referred toas a cushion module.

The lower flexible module 540 may have lower light transmittance thanthe flexible window module 530. For example, the flexible window module530 may have relatively high light transmittance and transmit the lightemitted from the display area DA of the flexible display module 510upward. The lower flexible module 540 may have a relatively lowtransmittance and may block the light which is emitted from the displayarea and, then, reflected in the flexible display module 510 toward thelower flexible module 540.

A third lower double-sided adhesive film NAD3 may be located between thelower flexible module 540 and the flexible display module 510. The lowerflexible module 540 may be attached to the lower surface of the flexibledisplay module 510 by the third lower double-sided adhesive film NAD3.The third lower double-sided adhesive film NAD3 may be a film having theadhesive properties to both the upper and lower surfaces, similarly tothe first and second upper double-sided adhesive films NAD1 and NAD2.The third lower double-sided adhesive film NAD3 may be the presssensitive adhesive (PSA).

The lower flexible module 540 may include an impact absorbing layer. Theimpact absorbing layer may prevent impact applied from the outside frombeing transferred to the flexible display module 510 from the bottom.For example, the impact absorbing layer may include polyurethane (PU),thermoplastic polyurethane (TPU), silicone (Si), polydimethylacrylamide(PDMA), or the like.

The rigid film 550 may overlap the lower flexible module 540 in thethickness direction and may be located below the lower flexible module540.

The rigid film 550 may include a metal material such as stainless steel(SUS), aluminum or the like. Alternatively, the rigid film 550 mayinclude a polymer such as polymethyl methacrylate (PMMA), polycarbonate(PC), polyvinylalcohol (PVA), acrylonitrile-butadiene-styrene (ABS),polyethylene terephthalate (PET), or the like. The rigid film 550 mayprevent the flexible display module 510 from being bent by externalforce or may alleviate or reduce the degree of bending (e.g., thebending angle and the bending radius of curvature) of the flexibledisplay module 510. For example, the rigid film 550 may maintain theflexible display module 510 in a relatively flat state even when anexternal force is applied. The rigid film 550 may be rigid orsemi-rigid. For example, the rigid film 550 may be a stainless steelfilm having a thickness of about 150 μm to about 200 μm. In exampleembodiments, the rigid film 550 may be an aluminum film having athickness of about 150 μm to about 200 μm.

A fourth lower double-sided adhesive film NAD4 may be located betweenthe rigid film 550 and the lower flexible module 540. The rigid film 550may be attached to the lower flexible module 540 by the fourth lowerdouble-sided adhesive film NAD4.

A protrusion, a groove or a hole may be formed on the lower surface ofthe rigid film 550. A foldable mobile terminal may include a housingcase to which the foldable display device 100 is coupled. The housingcase may be coupled to the rigid film 550 by the protrusion, the groove,or the hole such that the foldable display device 100 may be coupled tothe housing case.

As illustrated in FIG. 7 , at the fourth side K4 of the foldable displaydevice 100, a side surface S-1 a of the flexible display module 510, aside surface S-2 a of the flexible functional module 520, and a sidesurface S-3 a of the flexible window module 530 may be located on afirst plane.

An inner angle formed by the upper surface of the flexible window module530 and the first plane may be an acute angle. For example, the acuteangle may range from about 85 degrees to about 89 degrees or from about85 degrees to about 87 degrees.

At the fourth side K4 of the foldable display device 100, a side surfaceS-4 a of the lower flexible module 540 may be located on a second plane.The second plane may be located to be substantially closer to the centerof gravity of the foldable display device 100 than the first plane. Thesecond plane may be substantially non-parallel with the first plane. Forexample, the second plane may be substantially perpendicular to thedisplay surface of the flexible display module 510.

A side profile of the fourth side K4 of the foldable display device 100may be substantially similar to the side profile of the second side K2and the third side K3. Accordingly, descriptions of the side profiles ofthe second side K2 and the third side K3 will not be repeated.

As illustrated in FIG. 8 , the rigid film 550 may include a first plate841 (e.g., a first portion) and a second plate 842 (e.g., a secondportion) that are laterally separated from each other. The first plate841 and the second plate 842 may be located on substantially the sameplane and may be horizontally spaced apart from each other by areference separation distance D0. A reference separation distance D0 maybe about 0.1 mm or less. The first and second plates 841 and 842 may bemutually symmetric with respect to a folding line FL (e.g., a linemeeting the folding axis AXIS_F in the thickness direction).Alternatively, the first and second plates 841 and 842 may be mutuallyasymmetric with respect to the folding line FL.

In FIG. 8 , the first plate 841 and the second plate 842 may be spacedapart from each other. Alternatively, at least a portion of an innersurface of the first plate 841 may contact an inner surface of thesecond plate 842.

According to an example embodiment, the first plate 841 and the secondplate 842 may have a shape in which the thickness thereof decreases in adirection toward the folding line FL. The thicknesses of the first plate841 and the second plate 842 may be reduced stepwise. Alternatively, thethicknesses of the first plate 841 and the second plate 842 may becontinuously reduced. When the first plate 841 and the second plate 842have a shape in which the thickness is reduced toward the folding lineFL, portions of the first plate 841 and the second plate 842, theportions being near the folding line FL, may have substantially higherflexibilities than other portions the first plate 841 and the secondplate 842.

The fourth lower double-sided adhesive film NAD4 may include a firstdouble-sided adhesive film 851 (e.g., a third portion) and a seconddouble-sided adhesive film 852 (e.g., a fourth portion) which may beseparated from each other.

The first double-sided adhesive film 851 may overlap the flexibledisplay module 510 (e.g., the lower flexible module 540) in thethickness direction in a first non-foldable region NFR1 and may belocated between the lower flexible module 540 and the first plate 841.The first plate 841 may be coupled to the lower flexible module 540 bythe first double-sided adhesive film 851. Similarly, the seconddouble-sided adhesive film 852 may overlap the flexible display module510 (e.g., the lower flexible module 540) in a second non-foldableregion NFR2 and may be located between the lower flexible module 540 andthe second plate 842. The second plate 842 may be coupled to the lowerflexible module 540 by the second double-sided adhesive film 852.

The first double-sided adhesive film 851 and the second double-sidedadhesive film 852 may be located on substantially the same plane and maybe horizontally spaced apart from each other by a first separationdistance D1. The first separation distance D1 may be substantiallygreater than the reference separation distance D0. The first separationdistance D1 may be about 10 mm or less or about 7.5 mm or less. Thefirst double-sided adhesive film 851 and the second double-sidedadhesive film 852 may be horizontally symmetrical with respect to thefolding axis AXIS_F (e.g., a folding line or a folding face formed byextending the folding axis in the thickness direction).

The inner surface of the first plate 841 may be closer to the foldingline FL than the inner surface of the first double-sided adhesive film851. The inner surface of the second plate 842 may be closer to thefolding line FL of the inner surface than the second double-sidedadhesive film 852.

The foldable region FR and the first and second non-foldable regionsNFR1 and NFR2 of the flexible display module 510 may be set or definedby the first double-sided adhesive film 851 and the second double-sidedadhesive film 852. The foldable region FR and the first and secondnon-foldable regions NFR1 and NFR2 of foldable display device 100 may beset or defined by the first double-sided adhesive film 851 and thesecond double-sided adhesive film 852. The first and second non-foldableregions NFR1 and NFR2 may be regions where the first and second plates841 and 842 are coupled to the lower flexible module 540 by the firstand second double-sided adhesive films 851 and 852, respectively. Thefirst and second non-foldable regions NFR1 and NFR2 may have asubstantially small degree of bending due to the external force and mayhave a generally flat state. For example, the first and secondnon-foldable regions NFR1 and NFR2 may be defined as regions where therigid film 550 (e.g., the first and second plates 841 and 842), thefourth lower double-sided adhesive film NAD4 (e.g., the first and seconddouble-sided adhesive films 851 and 852), and the flexible displaymodule 510 simultaneously overlap each other and are coupled (e.g.,attached) to each other in the thickness direction. The foldable regionFR may be a region that is not directly coupled with (e.g., notsupported by) the first plate 841 and the second plate 842. The foldableregion FR may have a substantially large degree of bendability inresponse to an external force. For example, with respect to the sameexternal force, the degree of deformation (e.g., the degree of bending)of the foldable region FR may be about three times or more the degree ofdeformation of the first and second non-foldable regions NFR1 and NFR2.The foldable region FR may be switched from the folded state to theunfolded state by the external force or may be switched from theunfolded state to the folded state by the external force.

As illustrated in FIG. 6 , the foldable region FR may have asubstantially rectangular shape and may have a specific width to theleft and to the right with respect to the folding axis AXIS_F extendingup and down (e.g., in the vertical direction). The foldable region mayextend up and down from an upper side to a lower side. The width of thefoldable region FR may be substantially the same as or substantiallysimilar to the first separation distance D1 between the first and seconddouble-sided adhesive films 851 and 852.

The first non-foldable region NFR1 may be connected to one side (e.g.,the left side with respect to the folding axis AXIS_F) of the foldableregion FR and the second non-foldable region NFR2 may be connected tothe other side (e.g., the right side with respect to the folding axisAXIS_F) of the foldable region FR. The width of the first non-foldableregion NFR1 may be substantially equal to or substantially differentfrom the width of the second non-foldable region NFR2.

A neutral plane NP of the foldable display device 100 may be matched tothe flexible display module 510 of the flexible display module 510. Forexample, the neutral plane NP of the foldable display device 100 may bematched to a drive transistor TR of the flexible display module 510.

When the foldable display device 100 is bent or folded, a tensile stressmay be generated on one surface of the foldable display device 100 and acompressive stress may be generated on the other surface of the foldabledisplay device 100. In the middle, there may be a plane that is neitherexpanded nor contracted, which is defined as the neutral plane NP. Thereis substantially no bending stress on the neutral plane NP. For example,a higher neutral plane control unit HNPC and a lower neutral planecontrol unit LNPC may be used to place the neutral plane NP of thefoldable display device 100 in the flexible display module 510. Forexample, the higher neutral plane control unit HNPC and the lowerneutral plane control unit LNPC may place the neutral plane NP of thefoldable display device 100 in a layer in which the drive transistor ofthe flexible display module 510 is located.

As described above, the foldable region FR of the foldable displaydevice 100 may be defined by the first and second double-sided adhesivefilms 851 and 852 and the neutral plane NP may be placed in the flexibledisplay module 510 by the higher neutral plane control unit HNPC and thelower neutral plane control unit LNPC.

As illustrated in FIG. 9 , in a corner region (e.g., the first area A1)where the first and fourth sides K1 and K4 of the foldable displaydevice 100 meet, a side surface S-1 c of the flexible display module510, a side surface S-2 c of the flexible functional module 520, a sidesurface S-3 c of the flexible window module 530, and a side surface S-4c of the lower flexible module 540 may be located on substantiallydifferent planes.

The side surface S-3 c of the flexible window module 530 may be locatedoutside the side surface S-1 c of the flexible display module 510. Forexample, the side surface S-3 c of the flexible window module 530 may belocated outer than the side surface S-1 c of the flexible display module510.

The side surface S-2 c of the flexible functional module 520 may belocated inside the side surface S-1 c of the flexible display module510. For example, the side surface S-2 c of the flexible functionalmodule 520 may be located inner than the side surface S-1 c of theflexible display module 510.

The side surface S-4 c of the lower flexible module 540 may be locatedinside the side surface S-1 c of the flexible display module 510. Theside surface S-4 c of the lower flexible module 540 may be locatedoutside the side surface S-2 c of the flexible functional module 520.

The side surface of the rigid film 550 may be located on substantiallythe same plane as the side surface S-4 c of the lower flexible module540. For example, the side surface of the second plate 842 and the sidesurface of the second double-sided adhesive film 852 may be located onsubstantially the same plane as the side surface S-4 c of the lowerflexible module 540.

For example, in FIG. 9 , the side surface S-1 c of the flexible displaymodule 510, the side surface S-2 c of the flexible functional module520, the side surface S-3 c of the flexible window module 530, and theside surface S-4 c of the lower flexible module 540 may be substantiallyparallel with each other and may be substantially perpendicular to thedisplay surface of the flexible display module 510.

The flexible display module 510 may be formed by a laser cutting processusing laser light advancing in the first direction DL1 or in the seconddirection DL2 described with reference to FIG. 2 such that the sidesurface S-1 c of the flexible display module 510 may form an acute anglewith the display surface of the flexible display module 510. The acuteangle may be an inner angle ranging from about 85 degrees to about 89degrees. In this case, the side surface S-2 c of the flexible functionalmodule 520, the side surface S-3 c of the flexible window module 530,and the side surface S-4 c of the lower flexible module 540 may besubstantially perpendicular to the display surface of the flexibledisplay module 510.

The inorganic-inorganic contact closed loop LOOP_C in the flexibledisplay module 510 may be located inside the side surface S-2 c of theflexible functional module 520. The inorganic-inorganic contact closedloop LOOP_C in the flexible display module 510 may be located inside theside surface S-3 c of the flexible window module 530. Theinorganic-inorganic contact closed loop LOOP_C in the flexible displaymodule 510 may be located inside the side surface S-4 c of the flexiblewindow module 540.

As illustrated in FIG. 10 , the flexible display module 510 in thebendable region BR may be bent with a curvature radius R in the downwarddirection (e.g., the direction substantially opposite to the directionin which light from the display surface advances). The entire bendableregion BR may have a substantially constant curvature radius. In exampleembodiments, a portion of the bendable region BR may have asubstantially different curvature radius from another portion of thebendable region BR. The surface of the flexible display module 510 maybe inverted when the bendable region BR of the flexible display module510 is bent. For example, the surface of the flexible display module 510may include first to third portions. The first portion of the surface ofthe flexible display module 510 may face upwardly in the main region MR.The second portion of the surface of the flexible display module 510 maybe connected to the first portion of the flexible display module 510 andmay face outwardly in the bendable region BR. The third portion of thesurface of the flexible display module 510 may be connected to thesecond portion of the flexible display module 510 and may facedownwardly in the sub region SR.

After the bendable region BR is bent, the sub region SR may extend in adirection substantially parallel with the main region MR. After thebendable region BR is bent, the sub region SR may overlap the mainregion MR in the thickness direction of the flexible display module 510.After the bendable region BR is bent, the sub region SR may overlap thereduced non-display area RNDA of the main region MR. After the bendableregion BR is bent, the sub region SR may overlap the display area DA ofthe main region MR.

A fifth lower double-sided adhesive film NAD5 may be located between therigid film 550 (e.g., the second plate 842) and the sub region SR of theflexible display module 510. The sub region SR of the flexible displaymodule 510 may be attached to the rigid film 550.

A plurality of wires may be located in the bendable region BR and thesub region SR. The wires in the bendable region BR may be connected to acircuit layer of the main region MR and extend to the sub region SR. Thewires extending in the sub region SR may be connected to a circuit board1060. The circuit board 1060 may be a flexible printed circuit board.The circuit board 1060 may be provided in the form of film-on-plastic.For example, a contact pad of the circuit board 1060 exposed from anupper surface of the circuit board 1060 may be attached to a terminal ofthe wire in the sub region SR exposed from the lower surface of the subregion SR. The contact pad of the circuit board 1060 may be attached tothe terminal of the wire in the sub region SR by using an anisotropicconductive film.

A passivation film (e.g., a bendable region protective film) may belocated on the bendable region BR and the sub region SR of the flexibledisplay module 510. The passivation film may cover and protect wires.The passivation film may serve to reinforce the strength of the flexiblesubstrate or to alleviate the stress in the bendable region BR. Forexample, the passivation film may include an organic coating includingan organic material such as polyimide, acrylate, epoxy, or the like. Inexample embodiments, the passivation film may be a protective filmattached by an adhesive film.

In the vicinity of the first side K1 of the foldable display device 100,a side surface S-2 d of the flexible functional module 520, a sidesurface S-3 d of the flexible window module 530, and a side surface S-4d of the lower flexible module 540 may be located on substantiallydifferent planes. The relation of position among the side surface S-2 dof the flexible functional module 520, the side surface S-3 d of theflexible window module 530, and the side surface S-4 d of the lowerflexible module 540 may be substantially the same as the relation ofposition among the side surface S-2 c of the flexible functional module520, the side surface S-3 c of the flexible window module 530, and theside surface S-4 c of the lower flexible module 540. Therefore,redundant description will not be repeated.

The side surface S-3 d of the flexible window module 530 may be locatedon substantially the same plane as the outermost side of the bendableregion BR of the flexible display module 510. For example, the outersurface at an intermediate point B1 of the bendable region BR may belocated on substantially the same plane as the side surface S-3 d of theflexible window module 530. As described in FIG. 4 , a first side G1 ofthe preliminary flexible window module 130 may be located to passthrough the center of the bendable region BR (e.g., the bendable regionBR before bending). When the bendable region BR is bent, the outersurface at the intermediate point B1 of the bendable region BR maycoincide with the side surface S-3 d of the flexible window module 530depending on the curvature of the bendable region BR and the thicknessof the flexible window module 530.

As described with reference to FIGS. 6 to 10 , at the second to fourthsides K2, K3, and K4 of the foldable display device 100, the sidesurfaces of the flexible display module 510, the flexible functionalmodule 520, and the flexible window module 530 may have the reversetilted structure. Damage to the flexible display module 510 and laserequipment may be minimized during forming the second to fourth sides K2,K3, and K4 of the foldable display device 100. In addition, when theside surfaces of the flexible display module 510, the flexiblefunctional module 520, and the flexible window module 530 are arrangedon substantially the same plane, the foldable display device 100 may beefficiently inserted into the housing case as compared with a case wherethe side surfaces do not coincide with one another.

In addition, the inorganic-inorganic contact closed loop LOOP_C of theflexible display module 510 may be separated from the side surface(e.g., edge) of the flexible display module 510 and may be included inthe flexible display module 510. Accordingly, permeation of water,oxygen, or the like may be prevented.

FIG. 11 illustrates a plan view of a foldable display device accordingto an example embodiment.

Referring to FIG. 11 , a foldable display device 100_1 may include aflexible display module 1110. The flexible display module 1110 mayinclude the bendable region BR and the sub region SR described withreference to FIG. 1 .

The bendable region BR of the flexible display module 1110 may besubstantially the same as the bendable region BR of the flexible displaymodule 510. The bendable region BR of the flexible display module 1110may be substantially the same as the bendable region BR of thepreliminary flexible display module 110.

However, a length R2 (e.g., a vertical length) of the bendable region BRof the flexible display module 1110 may be substantially greater thanthe length of the bendable region BR of the flexible display module 510.The length R2 of the bendable region BR of the flexible display module1110 may be in a range of from about 50% to about 95%, or from about 65%to about 95% of the length R1 of the first side of the flexible displaymodule 1110 (e.g., a distance from the upper side to the lower side).

As the length R2 of the bendable region BR of the flexible displaymodule 1110 becomes substantially greater, the first area A1 (e.g., aregion having a cross section taken along line III-III′ described withreference to FIG. 3 ) may be decreased. In this case, it may be possibleto improve the robustness of the bendable region BR of the foldabledisplay device 100. In addition, a bending of an edge of the flexiblewindow module 530 that may be generated when a size of an area of theflexible window module 530 which is not supported by the flexibledisplay module 510 or the like decreases may be prevented.

FIG. 12 illustrates a plan view of the foldable display device accordingto an example embodiment.

Referring to FIG. 12 , a display device 100_2 may include a flexibledisplay module 1210, a flexible functional module 1220, and a flexiblewindow module 1230.

Each of the flexible display module 1210, the flexible functional module1220 and the flexible window module 1230 may have a cutout portion L-CUT(e.g., a cutting portion) formed on one side (e.g., an upper leftcorner). The cutout portion L-CUT may have a substantially rectangularshape. The flexible display module 1210, the flexible functional module1220, and the flexible window module 1230 may have a substantial “L”shape in a plan view.

The cutout portion L-CUT may be formed by the laser cutting describedwith reference to FIG. 5 such that the cross-section at the cutoutportion L-CUT may be substantially the same as the cross-sectiondescribed with reference to FIG. 7 .

The flexible display module 1210 may include an inorganic-inorganiccontact closed loop LOOP_C that does not overlap the cutout portionL-CUT. The inorganic-inorganic contact closed loop LOOP_C may include asubstantial “L” shape at the upper left side corresponding to the shapeof the cutout portion L-CUT and may be located to be spaced apart fromthe cutout portion L-CUT by a predetermined distance.

A length R3 (e.g., a vertical length) of a third side (e.g. a left sidenot in contact with the foldable region FR) of the foldable displaydevice 100 may be substantially smaller than the length R1 of the firstside (e.g., a right side) of the foldable display device 100. Forexample, a length of an outer side (e.g., a left side) of a firstnon-foldable region NFR1 may be substantially smaller than the length ofthe inner side (e.g., a right side) of the first non-foldable regionNFR1. The length of the outer side of the first non-foldable region NFR1may be substantially smaller than the length of the outer side of asecond non-foldable region NFR2.

The bendable region BR of the flexible display module 1210 may be formedon the first side substantially opposite to the third side based on thefoldable region FR or may extend from the first side.

A length R2 of the bendable region BR of the flexible display module1210 may be within a range of from about 50 to about 95% or a range offrom about 65 to about 95% of the length R1 (e.g., a distance from theupper side up to the lower side) of the first side of the flexibledisplay module 1210.

By way of summation and review, according to the foldable display deviceof an example embodiment, a side surface of a flexible display moduleand the side surface of a window module may form an acute angle with adisplay surface. Accordingly, damage to the flexible display module maybe minimized when the flexible display module and the window module arecut, a quality of a display device may be enhanced, and a width of thewindow module may be relatively reduced, thereby facilitating mountingof a housing case of the display device.

Example embodiments provide a foldable display device that is easilymanufactured and has enhanced quality and a manufacturing methodthereof.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular exampleembodiment may be used singly or in combination with features,characteristics, and/or elements described in connection with otherexample embodiments unless otherwise specifically indicated.Accordingly, it will be understood by those of skill in the art thatvarious changes in form and details may be made without departing fromthe spirit and scope thereof as set forth in the following claims.

What is claimed is:
 1. A foldable display device, comprising: a flexibledisplay module including a main region which has a display areaincluding an electroluminescent unit; a flexible functional module onthe flexible display module, the flexible functional module having atleast one function selected from a group of polarization, colorfiltering, color conversion, and touch sensing; a first double-sidedadhesive film on the flexible functional module; and a flexible windowmodule on the first double-sided adhesive film, wherein, at a first sideportion of the foldable display device, a side surface portion of astructure having the flexible display module and the flexible functionalmodule is located substantially on a first etching plane substantiallyon which a side surface portion of the flexible window module islocated, the first side portion of the foldable display device having afirst sidewall shape, the foldable display device has a second sideportion having a second sidewall shape substantially different from thefirst sidewall shape of the first side portion, at the second sideportion of the foldable display device, a side surface portion of theflexible window module is located substantially on a second plane, atthe second side portion of the foldable display device, a side surfaceportion of the flexible display module is located substantially on athird plane located inside the second plane in a plan view, and at thesecond side portion of the foldable display device, a side surfaceportion of the flexible functional module is located substantially on afourth plane located inside the third plane in a plan view.
 2. Thefoldable display device as claimed in claim 1, wherein, at the firstside portion of the foldable display device, a side surface portion ofthe flexible display module and a side surface portion the flexiblefunctional module are located substantially on the first etching plane.3. The foldable display device as claimed in claim 1, wherein a foldableregion of the foldable display device has a side portion which isincluded in the first side portion of the foldable display device. 4.The foldable display device as claimed in claim 1, further comprising: asecond double-sided adhesive film under the flexible display module; anda lower flexible module located under the second double-sided adhesivefilm, wherein, at the second side portion of the foldable displaydevice, a side surface portion of the lower flexible module is locatedsubstantially on a fifth plane located inside the third plane in a planview.
 5. The foldable display device as claimed in claim 1, wherein thefoldable display device has a third side portion having a third sidewallshape substantially different from the first and second sidewall shapesof the first and second side portions, and the flexible display modulefurther includes a sub region in which a pad is provided and a bentregion located at the third side portion of the foldable display deviceand bent between the main region and the sub region.
 6. The foldabledisplay device as claimed in claim 5, wherein, at the third side portionof the foldable display device, an outermost portion of the bent regionis aligned to be located just under a side surface portion of theflexible window module.
 7. The foldable display device as claimed inclaim 5, wherein the second side portion of the foldable display deviceis located between the first and third side portions of the foldabledisplay device in a plan view.
 8. The foldable display device as claimedin claim 7, wherein, at the first side portion of the foldable displaydevice, a side surface portion of the flexible display module and a sidesurface portion of the flexible functional module are locatedsubstantially on the first etching plane.
 9. The foldable display deviceas claimed in claim 8, wherein, at the third side portion of thefoldable display device, an outermost portion of the bent region isaligned to be located just under a side surface portion of the flexiblewindow module.
 10. The foldable display device as claimed in claim 5,wherein the foldable display device has a foldable region and anon-foldable region, the foldable region of the foldable display devicehas a side portion which is included in the first side portion of thefoldable display device, the third side portion of the foldable displaydevice is located in the non-foldable region of the foldable displaydevice, and the first side portion of the foldable display device issubstantially longer than the third side portion of the foldable displaydevice in a plan view.
 11. The foldable display device as claimed inclaim 1, wherein the first side portion of the foldable display devicecontinues to the second side portion of the foldable display device. 12.The foldable display device as claimed in claim 11, wherein the firstside portion of the foldable display device is substantially longer thanthe second side portion of the foldable display device in a plan view.13. The foldable display device as claimed in claim 11, wherein thefoldable display device has a foldable region and a non-foldable region,the foldable region of the foldable display device has a side portionwhich is included in the first side portion of the foldable displaydevice, and the second side portion of the foldable display device islocated in the non-foldable region of the foldable display device. 14.The foldable display device as claimed in claim 1, wherein the flexibledisplay module comprises: an encapsulation multilayer film on theelectroluminescent unit; a transistor electrically connected to theelectroluminescent unit; a first organic flexible film under thetransistor; a second double-sided adhesive film under the first organicflexible film; and a second organic flexible film under the seconddouble-sided adhesive film.
 15. The foldable display device as claimedin claim 14, wherein the foldable display device further comprises: athird double-sided adhesive film located under the flexible displaymodule; and a lower flexible module located under the third double-sidedadhesive film, and a base film is located under the lower flexiblemodule and has first and second rigid plate portions between which afoldable region of the foldable display device is located.
 16. Afoldable display device, comprising: a flexible display module includinga main region which has a display area including an electroluminescentunit; a flexible functional module on the flexible display module, theflexible functional module having at least one function selected from agroup of polarization, color filtering, color conversion, and touchsensing; a first double-sided adhesive film on the flexible functionalmodule; and a flexible window module on the first double-sided adhesivefilm, wherein, at a first side portion of the foldable display device, aside surface portion of a structure having the flexible display moduleand the flexible functional module is located substantially on a firstetching plane substantially on which a side surface portion of theflexible window module is located, the first side portion of thefoldable display device having a first sidewall shape, the foldabledisplay device has a second side portion having a second sidewall shapesubstantially different from the first sidewall shape of the first sideportion, at the second side portion of the foldable display device, aside surface portion of the flexible window module is locatedsubstantially on a second plane, at the second side portion of thefoldable display device, a side surface portion of the flexible displaymodule is located substantially on a third plane located inside thesecond plane in a plan view, the foldable display device has a thirdside portion having a third sidewall shape substantially different fromthe first and second sidewall shapes of the first and second sideportions, the flexible display module further includes a sub region inwhich a pad is provided and a bent region located at the third sideportion of the foldable display device and bent between the main regionand the sub region, and the second side portion of the foldable displaydevice is located between the first and third side portions of thefoldable display device in a plan view.
 17. The foldable display deviceas claimed in claim 16, wherein, at the first side portion of thefoldable display device, a side surface portion of the flexible displaymodule and a side surface portion of the flexible functional module arelocated substantially on the first etching plane.
 18. The foldabledisplay device as claimed in claim 16, wherein a foldable region of thefoldable display device has a side portion which is included in thefirst side portion of the foldable display device.
 19. The foldabledisplay device as claimed in claim 16, wherein, at the second sideportion of the foldable display device, a side surface portion of theflexible functional module is located substantially on a fourth planelocated inside the third plane in a plan view.
 20. The foldable displaydevice as claimed in claim 16, further comprising: a second double-sidedadhesive film under the flexible display module; and a lower flexiblemodule located under the second double-sided adhesive film, wherein, atthe second side portion of the foldable display device, a side surfaceportion of the lower flexible module is located substantially on a fifthplane located inside the third plane in a plan view.
 21. The foldabledisplay device as claimed in claim 16, wherein, at the third sideportion of the foldable display device, an outermost portion of the bentregion is aligned to be located just under a side surface portion of theflexible window module.
 22. The foldable display device as claimed inclaim 16, wherein, at the first side portion of the foldable displaydevice, a side surface portion of the flexible display module and a sidesurface portion of the flexible functional module are locatedsubstantially on the first etching plane, and wherein, at the secondside portion of the foldable display device, a side surface portion ofthe flexible functional module is located substantially on a fourthplane located inside the third plane in a plan view.
 23. The foldabledisplay device as claimed in claim 22, wherein, at the third sideportion of the foldable display device, an outermost portion of the bentregion is aligned to be located just under a side surface portion of theflexible window module.
 24. The foldable display device as claimed inclaim 16, wherein the foldable display device has a foldable region anda non-foldable region, the foldable region of the foldable displaydevice has a side portion which is included in the first side portion ofthe foldable display device, the third side portion of the foldabledisplay device is located in the non-foldable region of the foldabledisplay device, and the first side portion of the foldable displaydevice is substantially longer than the third side portion of thefoldable display device in a plan view.
 25. The foldable display deviceas claimed in claim 16, wherein the first side portion of the foldabledisplay device continues to the second side portion of the foldabledisplay device.
 26. The foldable display device as claimed in claim 16,wherein the first side portion of the foldable display device issubstantially longer than the second side portion of the foldabledisplay device in a plan view.
 27. The foldable display device asclaimed in claim 26, wherein the foldable display device has a foldableregion and a non-foldable region, the foldable region of the foldabledisplay device has a side portion which is included in the first sideportion of the foldable display device, and the second side portion ofthe foldable display device is located in the non-foldable region of thefoldable display device.
 28. The foldable display device as claimed inclaim 16, wherein the flexible display module comprises: anencapsulation multilayer film on the electroluminescent unit; atransistor electrically connected to the electroluminescent unit; afirst organic flexible film under the transistor; a second double-sidedadhesive film under the first organic flexible film; and a secondorganic flexible film under the second double-sided adhesive film. 29.The foldable display device as claimed in claim 28, wherein the foldabledisplay device further comprises: a third double-sided adhesive filmlocated under the flexible display module; and a lower flexible modulelocated under the third double-sided adhesive film, and a base film islocated under the lower flexible module and has first and second rigidplate portions between which a foldable region of the foldable displaydevice is located.
 30. A foldable display device, comprising: a flexibledisplay module including a main region which has a display areaincluding an electroluminescent unit; a flexible functional module onthe flexible display module, the flexible functional module having atleast one function selected from a group of polarization, colorfiltering, color conversion, and touch sensing; and a first double-sidedadhesive film on the flexible functional module; and a flexible windowmodule on the first double-sided adhesive film, wherein, at a first sideportion of the foldable display device, a side surface portion of theflexible functional module is located substantially on a first etchingplane substantially on which a side surface portion of the flexibledisplay module is located, the first side portion of the foldabledisplay device having a first sidewall shape, the foldable displaydevice has a second side portion having a second sidewall shapesubstantially different from the first sidewall shape of the first sideportion, at the second side portion of the foldable display device, aside surface portion of the flexible display module is locatedsubstantially on a third plane, at the second side portion of thefoldable display device, a side surface portion of the flexiblefunctional module is located substantially on a fourth plane locatedinside the third plane in a plan view, the foldable display device has athird side portion having a third sidewall shape substantially differentfrom the first and second sidewall shapes of the first and second sideportions, the flexible display module further includes a sub region inwhich a pad is provided and a bent region located at the third sideportion of the foldable display device and bent between the main regionand the sub region, and the second side portion of the foldable displaydevice is located between the first and third side portions of thefoldable display device in a plan view.
 31. The foldable display deviceas claimed in claim 30, wherein a foldable region of the foldabledisplay device has a side portion which is included in the first sideportion of the foldable display device.
 32. The foldable display deviceas claimed in claim 30, further comprising: a second double-sidedadhesive film under the flexible display module; and a lower flexiblemodule located under the second double-sided adhesive film, wherein, atthe second side portion of the foldable display device, a side surfaceportion of the lower flexible module is located substantially on a fifthplane located inside the third plane in a plan view.
 33. The foldabledisplay device as claimed in claim 30, wherein the foldable displaydevice has a foldable region and a non-foldable region, the foldableregion of the foldable display device has a side portion which isincluded in the first side portion of the foldable display device, thethird side portion of the foldable display device is located in thenon-foldable region of the foldable display device, and the first sideportion of the foldable display device is substantially longer than thethird side portion of the foldable display device in a plan view. 34.The foldable display device as claimed in claim 30, wherein, at thesecond side portion of the foldable display device, a side surfaceportion of the flexible window module is located substantially on asecond plane, and at the second side portion of the foldable displaydevice, at least one selected from a group of the side surface portionof the flexible display module and the side surface portion of theflexible functional module is not located substantially on the secondplane.
 35. The foldable display device as claimed in claim 34, wherein,at the second side portion of the foldable display device, the fourthplane is located substantially inside the second plane in a plan view.36. The foldable display device as claimed in claim 34, wherein thefirst side portion of the foldable display device continues to thesecond side portion of the foldable display device.
 37. The foldabledisplay device as claimed in claim 34, wherein the first side portion ofthe foldable display device is substantially longer than the second sideportion of the foldable display device in a plan view.
 38. The foldabledisplay device as claimed in claim 37, wherein the foldable displaydevice has a foldable region and a non-foldable region, the foldableregion of the foldable display device has a side portion which isincluded in the first side portion of the foldable display device, andthe second side portion of the foldable display device is located in thenon-foldable region of the foldable display device.
 39. The foldabledisplay device as claimed in claim 30, wherein the flexible displaymodule comprises: an encapsulation multilayer film on theelectroluminescent unit; a transistor electrically connected to theelectroluminescent unit; a first organic flexible film under thetransistor; a second double-sided adhesive film under the first organicflexible film; and a second organic flexible film under the seconddouble-sided adhesive film.
 40. The foldable display device as claimedin claim 39, wherein the foldable display device further comprises: athird double-sided adhesive film located under the flexible displaymodule; and a lower flexible module located under the third double-sidedadhesive film, and a base film is located under the lower flexiblemodule and has first and second rigid plate portions between which afoldable region of the foldable display device is located.
 41. Afoldable display device, comprising: a flexible display module includinga main region which has a display area including an electroluminescentunit; a flexible functional module on the flexible display module, theflexible functional module having at least one function selected from agroup of polarization, color filtering, color conversion, and touchsensing; and a first double-sided adhesive film on the flexiblefunctional module; and a flexible window module on the firstdouble-sided adhesive film, wherein, at a first side portion of thefoldable display device, a side surface portion of the flexiblefunctional module is located substantially on a first etching planesubstantially on which a side surface portion of the flexible displaymodule is located, the first side portion of the foldable display devicehaving a first sidewall shape, the foldable display device has a secondside portion having a second sidewall shape substantially different fromthe first sidewall shape of the first side portion, at the second sideportion of the foldable display device, a side surface portion of theflexible window module is located substantially on a second plane, atthe second side portion of the foldable display device, at least oneselected from a group of a side surface portion of the flexible displaymodule and a side surface portion of the flexible functional module isnot located substantially on the second plane, the foldable displaydevice has a third side portion having a third sidewall shapesubstantially different from the first and second sidewall shapes of thefirst and second side portions, the flexible display module furtherincludes a sub region in which a pad is provided and a bent regionlocated at the third side portion of the foldable display device andbent between the main region and the sub region, and the second sideportion of the foldable display device is located between the first andthird side portions of the foldable display device in a plan view. 42.The foldable display device as claimed in claim 41, wherein a foldableregion of the foldable display device has a side portion which isincluded in the first side portion of the foldable display device. 43.The foldable display device as claimed in claim 41, wherein, at thesecond side portion of the foldable display device, the side surfaceportion of the flexible display module is located substantially on athird plane, and at the second side portion of the foldable displaydevice, the side surface portion of the flexible functional module islocated substantially on a fourth plane located inside the third planein a plan view, the foldable display device further comprises: a seconddouble-sided adhesive film under the flexible display module; and alower flexible module located under the second double-sided adhesivefilm, and at the second side portion of the foldable display device, aside surface portion of the lower flexible module is locatedsubstantially on a fifth plane located inside the third plane in a planview.
 44. The foldable display device as claimed in claim 43, wherein,at the second side portion of the foldable display device, the fourthplane is located substantially inside the second plane in a plan view.45. The foldable display device as claimed in claim 41, wherein thefoldable display device has a foldable region and a non-foldable region,the foldable region of the foldable display device has a side portionwhich is included in the first side portion of the foldable displaydevice, the third side portion of the foldable display device is locatedin the non-foldable region of the foldable display device, and the firstside portion of the foldable display device is substantially longer thanthe third side portion of the foldable display device in a plan view.46. The foldable display device as claimed in claim 41, wherein thefirst side portion of the foldable display device continues to thesecond side portion of the foldable display device.
 47. The foldabledisplay device as claimed in claim 41, wherein the first side portion ofthe foldable display device is substantially longer than the second sideportion of the foldable display device in a plan view.
 48. The foldabledisplay device as claimed in claim 47, wherein the foldable displaydevice has a foldable region and a non-foldable region, the foldableregion of the foldable display device has a side portion which isincluded in the first side portion of the foldable display device, andthe second side portion of the foldable display device is located in thenon-foldable region of the foldable display device.
 49. The foldabledisplay device as claimed in claim 41, wherein the flexible displaymodule comprises: an encapsulation multilayer film on theelectroluminescent unit; a transistor electrically connected to theelectroluminescent unit; a first organic flexible film under thetransistor; a second double-sided adhesive film under the first organicflexible film; and a second organic flexible film under the seconddouble-sided adhesive film.
 50. The foldable display device as claimedin claim 49, wherein the foldable display device further comprises: athird double-sided adhesive film located under the flexible displaymodule; and a lower flexible module located under the third double-sidedadhesive film, a base film is located under the lower flexible moduleand has first and second rigid plate portions between which a foldableregion of the foldable display device is located.
 51. A mobile terminalwith a foldable display device, the foldable display device providing animage displayed from the mobile terminal, wherein the improvementcomprises that the foldable display device comprises: a flexible displaymodule including a main region which has a display area including anelectroluminescent unit; a flexible functional module on the flexibledisplay module, the flexible functional module having at least onefunction selected from a group of polarization, color filtering, colorconversion, and touch sensing; a first double-sided adhesive film on theflexible functional module; and a flexible window module on the firstdouble-sided adhesive film, wherein, at a first side portion of thefoldable display device, a side surface portion of a structure havingthe flexible display module and the flexible functional module islocated substantially on a first etching plane substantially on which aside surface portion of the flexible window module is located, the firstside portion of the foldable display device having a first sidewallshape, the foldable display device has a second side portion having asecond sidewall shape substantially different from the first sidewallshape of the first side portion, at the second side portion of thefoldable display device, a side surface portion of the flexible windowmodule is located substantially on a second plane, at the second sideportion of the foldable display device, a side surface portion of theflexible display module is located substantially on a third planelocated inside the second plane in a plan view, and at the second sideportion of the foldable display device, a side surface portion of theflexible functional module is located substantially on a fourth planelocated inside the third plane in a plan view.
 52. The mobile terminalas claimed in claim 51, wherein, at the first side portion of thefoldable display device, a side surface portion of the flexible displaymodule and a side surface portion the flexible functional module arelocated substantially on the first etching plane.
 53. The mobileterminal as claimed in claim 51, wherein a foldable region of thefoldable display device has a side portion which is included in thefirst side portion of the foldable display device.
 54. The mobileterminal as claimed in claim 51, further comprising: a seconddouble-sided adhesive film under the flexible display module; and alower flexible module located under the second double-sided adhesivefilm, wherein, at the second side portion of the foldable displaydevice, a side surface portion of the lower flexible module is locatedsubstantially on a fifth plane located inside the third plane in a planview.
 55. The mobile terminal as claimed in claim 51, wherein thefoldable display device has a third side portion having a third sidewallshape substantially different from the first and second sidewall shapesof the first and second side portions, and the flexible display modulefurther includes a sub region in which a pad is provided and a bentregion located at the third side portion of the foldable display deviceand bent between the main region and the sub region.
 56. The mobileterminal as claimed in claim 55, wherein, at the third side portion ofthe foldable display device, an outermost portion of the bent region isaligned to be located just under a side surface portion of the flexiblewindow module.
 57. The mobile terminal as claimed in claim 55, whereinthe second side portion of the foldable display device is locatedbetween the first and third side portions of the foldable display devicein a plan view.
 58. The mobile terminal as claimed in claim 57, wherein,at the first side portion of the foldable display device, a side surfaceportion of the flexible display module and a side surface portion of theflexible functional module are located substantially on the firstetching plane.
 59. The mobile terminal as claimed in claim 58, wherein,at the third side portion of the foldable display device, an outermostportion of the bent region is aligned to be located just under a sidesurface portion of the flexible window module.
 60. The mobile terminalas claimed in claim 55, wherein the foldable display device has afoldable region and a non-foldable region, the foldable region of thefoldable display device has a side portion which is included in thefirst side portion of the foldable display device, the third sideportion of the foldable display device is located in the non-foldableregion of the foldable display device, and the first side portion of thefoldable display device is substantially longer than the third sideportion of the foldable display device in a plan view.
 61. The mobileterminal as claimed in claim 51, wherein the first side portion of thefoldable display device continues to the second side portion of thefoldable display device.
 62. The mobile terminal as claimed in claim 61,wherein the first side portion of the foldable display device issubstantially longer than the second side portion of the foldabledisplay device in a plan view.
 63. The mobile terminal as claimed inclaim 61, wherein the foldable display device has a foldable region anda non-foldable region, the foldable region of the foldable displaydevice has a side portion which is included in the first side portion ofthe foldable display device, and the second side portion of the foldabledisplay device is located in the non-foldable region of the foldabledisplay device.
 64. The mobile terminal as claimed in claim 51, whereinthe flexible display module comprises: an encapsulation multilayer filmon the electroluminescent unit; a transistor electrically connected tothe electroluminescent unit; a first organic flexible film under thetransistor; a second double-sided adhesive film under the first organicflexible film; and a second organic flexible film under the seconddouble-sided adhesive film.
 65. The mobile terminal as claimed in claim64, wherein the foldable display device further comprises: a thirddouble-sided adhesive film located under the flexible display module;and a lower flexible module located under the third double-sidedadhesive film, and a base film is located under the lower flexiblemodule and has first and second rigid plate portions between which afoldable region of the foldable display device is located.
 66. A mobileterminal with a foldable display device, the foldable display deviceproviding an image displayed from the mobile terminal, wherein theimprovement comprises that the foldable display device comprises: aflexible display module including a main region which has a display areaincluding an electroluminescent unit; a flexible functional module onthe flexible display module, the flexible functional module having atleast one function selected from a group of polarization, colorfiltering, color conversion, and touch sensing; a first double-sidedadhesive film on the flexible functional module; and a flexible windowmodule on the first double-sided adhesive film, wherein, at a first sideportion of the foldable display device, a side surface portion of astructure having the flexible display module and the flexible functionalmodule is located substantially on a first etching plane substantiallyon which a side surface portion of the flexible window module islocated, the first side portion of the foldable display device having afirst sidewall shape, the foldable display device has a second sideportion having a second sidewall shape substantially different from thefirst sidewall shape of the first side portion, at the second sideportion of the foldable display device, a side surface portion of theflexible window module is located substantially on a second plane, atthe second side portion of the foldable display device, a side surfaceportion of the flexible display module is located substantially on athird plane located inside the second plane in a plan view, the foldabledisplay device has a third side portion having a third sidewall shapesubstantially different from the first and second sidewall shapes of thefirst and second side portions, the flexible display module furtherincludes a sub region in which a pad is provided and a bent regionlocated at the third side portion of the foldable display device andbent between the main region and the sub region, and the second sideportion of the foldable display device is located between the first andthird side portions of the foldable display device in a plan view. 67.The mobile terminal as claimed in claim 66, wherein, at the first sideportion of the foldable display device, a side surface portion of theflexible display module and a side surface portion of the flexiblefunctional module are located substantially on the first etching plane.68. The mobile terminal as claimed in claim 66, wherein a foldableregion of the foldable display device has a side portion which isincluded in the first side portion of the foldable display device. 69.The mobile terminal as claimed in claim 66, wherein, at the second sideportion of the foldable display device, a side surface portion of theflexible functional module is located substantially on a fourth planelocated inside the third plane in a plan view.
 70. The mobile terminalas claimed in claim 66, further comprising: a second double-sidedadhesive film under the flexible display module; and a lower flexiblemodule located under the second double-sided adhesive film, wherein, atthe second side portion of the foldable display device, a side surfaceportion of the lower flexible module is located substantially on a fifthplane located inside the third plane in a plan view.
 71. The mobileterminal as claimed in claim 66, wherein, at the third side portion ofthe foldable display device, an outermost portion of the bent region isaligned to be located just under a side surface portion of the flexiblewindow module.
 72. The mobile terminal as claimed in claim 66, wherein,at the first side portion of the foldable display device, a side surfaceportion of the flexible display module and a side surface portion of theflexible functional module are located substantially on the firstetching plane, and wherein, at the second side portion of the foldabledisplay device, a side surface portion of the flexible functional moduleis located substantially on a fourth plane located inside the thirdplane in a plan view.
 73. The mobile terminal as claimed in claim 72,wherein, at the third side portion of the foldable display device, anoutermost portion of the bent region is aligned to be located just undera side surface portion of the flexible window module.
 74. The mobileterminal as claimed in claim 66, wherein the foldable display device hasa foldable region and a non-foldable region, the foldable region of thefoldable display device has a side portion which is included in thefirst side portion of the foldable display device, the third sideportion of the foldable display device is located in the non-foldableregion of the foldable display device, and the first side portion of thefoldable display device is substantially longer than the third sideportion of the foldable display device in a plan view.
 75. The mobileterminal as claimed in claim 66, wherein the first side portion of thefoldable display device continues to the second side portion of thefoldable display device.
 76. The mobile terminal as claimed in claim 66,wherein the first side portion of the foldable display device issubstantially longer than the second side portion of the foldabledisplay device in a plan view.
 77. The mobile terminal as claimed inclaim 76, wherein the foldable display device has a foldable region anda non-foldable region, the foldable region of the foldable displaydevice has a side portion which is included in the first side portion ofthe foldable display device, and the second side portion of the foldabledisplay device is located in the non-foldable region of the foldabledisplay device.
 78. The mobile terminal as claimed in claim 66, whereinthe flexible display module comprises: an encapsulation multilayer filmon the electroluminescent unit; a transistor electrically connected tothe electroluminescent unit; a first organic flexible film under thetransistor; a second double-sided adhesive film under the first organicflexible film; and a second organic flexible film under the seconddouble-sided adhesive film.
 79. The mobile terminal as claimed in claim78, wherein the foldable display device further comprises: a thirddouble-sided adhesive film located under the flexible display module;and a lower flexible module located under the third double-sidedadhesive film, and a base film is located under the lower flexiblemodule and has first and second rigid plate portions between which afoldable region of the foldable display device is located.
 80. A mobileterminal with a foldable display device, the foldable display deviceproviding an image displayed from the mobile terminal, wherein theimprovement comprises that the foldable display device comprises: aflexible display module including a main region which has a display areaincluding an electroluminescent unit; a flexible functional module onthe flexible display module, the flexible functional module having atleast one function selected from a group of polarization, colorfiltering, color conversion, and touch sensing; and a first double-sidedadhesive film on the flexible functional module; and a flexible windowmodule on the first double-sided adhesive film, wherein, at a first sideportion of the foldable display device, a side surface portion of theflexible functional module is located substantially on a first etchingplane substantially on which a side surface portion of the flexibledisplay module is located, the first side portion of the foldabledisplay device having a first sidewall shape, the foldable displaydevice has a second side portion having a second sidewall shapesubstantially different from the first sidewall shape of the first sideportion, at the second side portion of the foldable display device, aside surface portion of the flexible display module is locatedsubstantially on a third plane, at the second side portion of thefoldable display device, a side surface portion of the flexiblefunctional module is located substantially on a fourth plane locatedinside the third plane in a plan view, the foldable display device has athird side portion having a third sidewall shape substantially differentfrom the first and second sidewall shapes of the first and second sideportions, the flexible display module further includes a sub region inwhich a pad is provided and a bent region located at the third sideportion of the foldable display device and bent between the main regionand the sub region, and the second side portion of the foldable displaydevice is located between the first and third side portions of thefoldable display device in a plan view.
 81. The mobile terminal asclaimed in claim 80, wherein a foldable region of the foldable displaydevice has a side portion which is included in the first side portion ofthe foldable display device.
 82. The mobile terminal as claimed in claim80, further comprising: a second double-sided adhesive film under theflexible display module; and a lower flexible module located under thesecond double-sided adhesive film, wherein, at the second side portionof the foldable display device, a side surface portion of the lowerflexible module is located substantially on a fifth plane located insidethe third plane in a plan view.
 83. The mobile terminal as claimed inclaim 80, wherein the foldable display device has a foldable region anda non-foldable region, the foldable region of the foldable displaydevice has a side portion which is included in the first side portion ofthe foldable display device, the third side portion of the foldabledisplay device is located in the non-foldable region of the foldabledisplay device, and the first side portion of the foldable displaydevice is substantially longer than the third side portion of thefoldable display device in a plan view.
 84. The mobile terminal asclaimed in claim 80, wherein at the second side portion of the foldabledisplay device, a side surface portion of the flexible window module islocated substantially on a second plane, and at the second side portionof the foldable display device, at least one selected from a group ofthe side surface portion of the flexible display module and the sidesurface portion of the flexible functional module is not locatedsubstantially on the second plane.
 85. The mobile terminal as claimed inclaim 84, wherein the first side portion of the foldable display devicecontinues to the second side portion of the foldable display device. 86.The mobile terminal as claimed in claim 84, wherein the first sideportion of the foldable display device is substantially longer than thesecond side portion of the foldable display device in a plan view. 87.The mobile terminal as claimed in claim 86, wherein the foldable displaydevice has a foldable region and a non-foldable region, the foldableregion of the foldable display device has a side portion which isincluded in the first side portion of the foldable display device, andthe second side portion of the foldable display device is located in thenon-foldable region of the foldable display device.
 88. The mobileterminal as claimed in claim 84, wherein, at the second side portion ofthe foldable display device, the fourth plane is located substantiallyinside the second plane in a plan view.
 89. The mobile terminal asclaimed in claim 80, wherein the flexible display module comprises: anencapsulation multilayer film on the electroluminescent unit; atransistor electrically connected to the electroluminescent unit; afirst organic flexible film under the transistor; a second double-sidedadhesive film under the first organic flexible film; and a secondorganic flexible film under the second double-sided adhesive film. 90.The mobile terminal as claimed in claim 89, wherein the foldable displaydevice further comprises: a third double-sided adhesive film locatedunder the flexible display module; and a lower flexible module locatedunder the third double-sided adhesive film, and a base film is locatedunder the lower flexible module and has first and second rigid plateportions between which a foldable region of the foldable display deviceis located.
 91. A mobile terminal with a foldable display device, thefoldable display device providing an image displayed from the mobileterminal, wherein the improvement comprises that the foldable displaydevice comprises: a flexible display module including a main regionwhich has a display area including an electroluminescent unit; aflexible functional module on the flexible display module, the flexiblefunctional module having at least one function selected from a group ofpolarization, color filtering, color conversion, and touch sensing; anda first double-sided adhesive film on the flexible functional module;and a flexible window module on the first double-sided adhesive film,wherein, at a first side portion of the foldable display device, a sidesurface portion of the flexible functional module is locatedsubstantially on a first etching plane substantially on which a sidesurface portion of the flexible display module is located, the firstside portion of the foldable display device having a first sidewallshape, the foldable display device has a second side portion having asecond sidewall shape substantially different from the first sidewallshape of the first side portion, at the second side portion of thefoldable display device, a side surface portion of the flexible windowmodule is located substantially on a second plane, at the second sideportion of the foldable display device, at least one selected from agroup of a side surface portion of the flexible display module and aside surface portion of the flexible functional module is not locatedsubstantially on the second plane, the foldable display device has athird side portion having a third sidewall shape substantially differentfrom the first and second sidewall shapes of the first and second sideportions, the flexible display module further includes a sub region inwhich a pad is provided and a bent region located at the third sideportion of the foldable display device and bent between the main regionand the sub region, and the second side portion of the foldable displaydevice is located between the first and third side portions of thefoldable display device in a plan view.
 92. The mobile terminal asclaimed in claim 91, wherein a foldable region of the foldable displaydevice has a side portion which is included in the first side portion ofthe foldable display device.
 93. The mobile terminal as claimed in claim91, wherein at the second side portion of the foldable display device,the side surface portion of the flexible display module is locatedsubstantially on a third plane, at the second side portion of thefoldable display device, the side surface portion of the flexiblefunctional module is located substantially on a fourth plane locatedinside the third plane in a plan view, the foldable display devicefurther comprises: a second double-sided adhesive film under theflexible display module; and a lower flexible module located under thesecond double-sided adhesive film, and at the second side portion of thefoldable display device, a side surface portion of the lower flexiblemodule is located substantially on a fifth plane located inside thethird plane in a plan view.
 94. The mobile terminal as claimed in claim93, wherein, at the second side portion of the foldable display device,the fourth plane is located substantially inside the second plane in aplan view.
 95. The mobile terminal as claimed in claim 91, wherein thefoldable display device has a foldable region and a non-foldable region,the foldable region of the foldable display device has a side portionwhich is included in the first side portion of the foldable displaydevice, the third side portion of the foldable display device is locatedin the non-foldable region of the foldable display device, and the firstside portion of the foldable display device is substantially longer thanthe third side portion of the foldable display device in a plan view.96. The mobile terminal as claimed in claim 91, wherein the first sideportion of the foldable display device continues to the second sideportion of the foldable display device.
 97. The mobile terminal asclaimed in claim 91, wherein the first side portion of the foldabledisplay device is substantially longer than the second side portion ofthe foldable display device in a plan view.
 98. The mobile terminal asclaimed in claim 97, wherein the foldable display device has a foldableregion and a non-foldable region, the foldable region of the foldabledisplay device has a side portion which is included in the first sideportion of the foldable display device, and the second side portion ofthe foldable display device is located in the non-foldable region of thefoldable display device.
 99. The mobile terminal as claimed in claim 91,wherein the flexible display module comprises: an encapsulationmultilayer film on the electroluminescent unit; a transistorelectrically connected to the electroluminescent unit; a first organicflexible film under the transistor; a second double-sided adhesive filmunder the first organic flexible film; and a second organic flexiblefilm under the second double-sided adhesive film.
 100. The mobileterminal as claimed in claim 99, wherein the foldable display devicefurther comprises: a third double-sided adhesive film located under theflexible display module; and a lower flexible module located under thethird double-sided adhesive film, and a base film is located under thelower flexible module and has first and second rigid plate portionsbetween which a foldable region of the foldable display device islocated.